In this proposal we aim to study low temperature structure of hydrogen in the interlayer region of partially hydrated pillared clays. There are linked dual motivations for this experiment: (i) understanding the fundamental (quantum) properties of confined molecular hydrogen, and; (ii) the search for improved hydrogen storage materials. We will study H2 in synthetic high charge Ca- and Mg-laponite and natural Ca- and Mg-vermiculite. The laponites are produced as ~100-500nm discs, while the vermiculite occurs naturally as macroscopic (mm2) crystallites. Before each experiment the samples will be treated with D2O to expand the interlayer region to around 3.5 ¿ 6.0 Å, and then be baked out at between 140C. Sequential dosing with H2 will be conducted in situ around 100K and < 2 bar. We are particularly interested in the clay-clay d-spacing: does the clay have to expand to accommodate H2?